Floor Building Panels

Product information

Whether for new construction or a renovation, a great variety of subfloor types need a tile underlayment prior to setting tile or stone. Some reasons for the need to install tile underlayments include: they may reduce stresses from subfloors and protect tile, they may be used to build up height as needed to finish the tile surface flush with adjacent flooring surface, and they may be necessary for waterproofing or insulation purposes. They should also provide and support successful and lasting adhesion performance for thinset mortar and tile.

wedi® Building Panels offer a durable underlayment surface once tiled and pass the Robinson Floor Test (ASTM C627) with a “heavy duty use“ rating.  In combination with its ideal flat surface, it is a logical choice when installing small tile or very large tile, extremely thin tile on floors. Both require perfect thinset mortar coverage and adhesion, made easy when working on a most flat and even surfaces, and the full support of a strong underlayment like the wedi Building Panel.

However, it is important to evaluate the suitability of a subfloor structure, or the layer below a tile underlayment, to ensure a proper tile installation and the choice of a good underlayment fitting the application.

wedi® Building Panels are:

  • Used in wet rooms, or where floor warming systems are used
  • Ready for tiling upon installation
  • 100% waterproof due to their extruded polystyrene (closed-cell) foam core
  • Easy and clean to cut to size using a utility knife, circular saw, or handsaw
  • Available in sizes and thicknesses that can accommodate different projects and applications
Ghost Accordion

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Building Panel Video
Installation Manual, Requirements/Limitations and Warranty
Product Approvals & Certification

Approvals and certificates applicable to entire Fundo Shower System incl. wedi Building Panel:

City of New York, MEA 912-52-SM

Fundo Shower Systems & Building Panels: ICC PMG 1189 (for USA & Canada) – Download Here

Meets all applicable ANSI/ISO Standards incl. ANSI 118.10 and IAPMO PS106

TCNA handbook recognized for wall, floor, countertop, & more applications

City of Los Angeles Approval M-100017

BBA (British Board of Agrement)


CE Marked

Diverse State Approvals

SAI Global Watermark Certified (Australia & New Zealand)

Codemark Certified (Australia & New Zealand)

Technical Performance Data

ASTM C 578
Thermal Conductivity
Tensile Strength
Shear Strength
Flexural Strength
Fungus/Bacteria Resistance
Linear Variation
Seam Strength
Robinson Floor Test
Fastener Pull Through
Temperature Limits
Freeze & Thaw
Accelerated Aging
Surface Burning Characteristics
Standard Specification for Rigid, Cellular Polystyrene
75°F (25°C) - ASTM C518
75°F (25°) - ASTM C518
Under conditions required in ANSI A118.10-1999
ASTM D4068 / ANSI A118.10-1999
AC 159/ASTM 1037-39
ASTM D751-11 (requirement 8 lb/in width)
ASTM C666 - 25 Cycles
AC 71 - 25 Cycles
ASTM E84-16 (NFPA 255, ANSI / UL 723, UBC 8-1) Tested as required without tile on Building Panel surface
0.23 Bbtu in/hr F
4.3hr ft. 2 F/Btu/in (R Value for 1” wedi = 4.3)
65 psi
4 week Shear Strength Dry: 216 psi 12 week Shear Strength Dry: 217 psi 100 day Shear Strength Wet: 201 psi
627 PSI
Passed, No Growth
Passed, less than 0.07%
Passed, 36.4 lbs
Heavy duty commercial use, passed
Wet 131.8 lb./Dry 196.2 lb.
-58 / +165° F
No disintegration/change; Passed
No disintegration; Passed
Flame Spread Index (FSI): 20 | Smoke Developed Index (SDI) : 70 |Classification: Class A

Product Sizes

To determine the size and quantity of wedi Building Panels you will need for your shower, please follow the steps outlined below: 

  1. Calculate the total area of the shower wall
    1. Multiply L x H of the wall. The height of each wall will be determined based on how high you plan to install the tile
    2.  Add the calculated square footage of each wall together to determine the combined sum of all the shower walls
    3. Multiply the combined area of all shower walls by 1.15 to account for about 15% extra square feet of building panel for any waste cuts
  2. Divide the total area of the shower walls by the square foot area of the wedi building panels you plan to us4 (e.g. 4×5 ft. building panel = 20 square feet)
    1. A total shower wall area of 115 square feet divided by 20 square feet per building panel gives us a total of 5.75 building panels.
    2. Remember to always round up to the next whole building panel. 

For product retail pricing, please see our Illustrated Retail Price List (USA or CA), available in the downloads section below.

Main Application
Item Number
Backsplash, tub decks, floors, under mosaic strips in field tile designs
24 in. x 48 in. x 1/8 in.
10 sheets/box
Tub decks, floors, with electric radiant heat
48 in. x 60 in. x 1/4 in.
25 sheets/pallet
Floor panel, aligns with Fundo Curbless Shower Bases to create extension to bathroom floor
48 in. x 60 in. x 3/4 in.
4 sheets/box
Constructing benches, floors to line up with Fundo Shower Bases into bathroom
48 in. x 60 in. x 1 1/2 in.
2 sheets/box

Step 2 Complete!

You’ve chosen your building panels, now choose your prefab modules!

Additional Downloads